[Vicky82]

Mutagen Man isn't forgotten, he was mentioned in the last episode and anyway it's going to take about 70 years for Mutagen Man to thaw out, Donnie said it in The Invasion.

Also if you remember the Mutagen Man episode, the ice he's under isn't normal ice it has got mutagen in it. It was a failed retro mutagen

So the only time we are going to see Mutagen Man completely thawed out is that they have an episode that takes place 70+ years in the future, which I can't see happening anyway.

So we are done with Mutagen Man and he's a **** character anyway.